Characteristics of U.S. Adults with Usual Daily Folic Acid Intake above the Tolerable Upper Intake Level: National Health and Nutrition Examination Survey, 2003-2010.

Angela Orozco,Robert Berry,Jing Guo,Alicia Carriquiry,Lorraine Yeung

doi:10.3390/nu8040195

Abstract

The Food and Drug Administration mandated that by 1998, all enriched cereal grain products (ECGP) be fortified with folic acid in order to prevent the occurrence of neural tube defects. The Institute of Medicine established the tolerable upper intake level (UL) for folic acid (1000 µg/day for adults) in 1998. We characterized U.S. adults with usual daily folic acid intake exceeding the UL. Using NHANES 2003–2010 data, we estimated the percentage of 18,321 non-pregnant adults with usual daily folic acid intake exceeding the UL, and among them, we calculated the weighted percentage by sex, age, race/ethnicity, sources of folic acid intake, supplement use and median usual daily folic acid intakes. Overall, 2.7% (standard error 0.6%) of participants had usual daily intake exceeding the UL for folic acid; 62.2% were women; 86.3% were non-Hispanic whites; and 98.5% took supplements containing folic acid. When stratified by sex and age groups among those with usual daily folic acid intake exceeding the UL, 20.8% were women aged 19–39 years. Those with usual daily intake exceeding the folic acid UL were more likely to be female, non-Hispanic white, supplement users or to have at least one chronic medical condition compared to those not exceeding the folic acid UL. Among those with usual daily folic acid intake exceeding the UL who also took supplements, 86.6% took on average >400 µg of folic acid/day from supplements. Everyone with usual daily folic acid intake exceeding the UL consumed folic acid from multiple sources. No one in our study population had usual daily folic acid intake exceeding the UL through consumption of mandatorily-fortified enriched cereal grain products alone. Voluntary consumption of supplements containing folic acid is the main factor associated with usual daily intake exceeding the folic acid UL.

Highlights

Folic acid reduces a woman’s risk of having a child affected by a neural tube defect, such as spina bifida [1,2]
Adults, 2.7% had usual daily folic acid intake exceeding the upper intake level (UL). Those with usual daily folic acid intake exceeding the UL were more likely to be female (62.2% compared to 51.9%; p = 0.001), non-Hispanic white (86.3% compared to 72.2%; p < 0.0001), supplement users
The distributions of age groups were significantly different among those with usual daily folic acid intake exceeding the UL compared to those with intake not exceeding the UL. Those aged ě60 years made up a significantly greater proportion among those with usual daily folic acid intake exceeding the UL compared to those with intake not exceeding the UL (34.4% vs. 24.8%, p < 0.02). Among those with usual daily folic acid intake exceeding the UL, 20.8% were women aged 19–39 years and 19.9%

Summary

Introduction

Folic acid reduces a woman’s risk of having a child affected by a neural tube defect, such as spina bifida [1,2]. The IOM identified 5000 μg/day as the lowest observed adverse effect level (LOAEL) for folic acid and established a tolerable upper intake level (UL) (1000 μg/day for adults) for folic acid by dividing the LOAEL by an uncertainty factor of five [4]. Studies have found that less than 3% of U.S adults had usual daily folic acid intake exceeding the UL post-fortification [5,6]; among those aged >50 years, approximately 5% had usual daily folic acid intake exceeding the UL [7]. No studies have described the characteristics of adults with usual daily intake of folic acid exceeding the UL. We aim to characterize U.S adults with usual daily intake of folic acid exceeding the UL and describe their sources of folic acid consumption

Objectives

Methods

Results

Discussion

Conclusion